Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A common mutation (C677-->T) in methylenetetrahydrofolate (MTHFR) gene, involved in the metabolism of homocysteine, has been suggested to play a role in increasing cardiovascular disease risk. We determined the frequency of C677-->T genotypes and alleles in 155 Caucasian patients with angiographically documented coronary artery disease (CAD) and in 155 age and sex matched normal Caucasian individuals. DNA was extracted from the blood and genotypes were determined by polymerase chain reaction, restriction mapping with HinfI and gel electrophoresis. The distribution of MTHFR C677-->T genotypes followed the Hardy-Weinberg equilibrium. The distribution of MTHFR genotypes and the frequency of alleles were similar in cases and controls. The TT genotype was present in 8% of controls as compared to 6% of cases (P = 0.50, OR = 0.82; 95% CI: 0.34-1.96). The frequency of T allele was also similar in patients with CAD compared with controls (0.29 vs. 0.33; P = 0.29). There was also no significant association between C677-->T genotypes and the risk of myocardial infarction. In a subgroup of 44 cases and 89 controls who had no conventional risk factors for CAD (hyperlipidemia, hypertension, diabetes mellitus, and smoking), the frequency of TT genotype was similar (11% vs. 8%, respectively, P = 0.71, OR: 0.67, 95% CI: 0.20-2.23). Thus, the MTHFR TT genotype is not a major genetic risk factor for predisposition to CAD and its thrombotic complications in this population.
Atherosclerosis 1997 Jan 03
PMID:A common mutation in methylenetetrahydrofolate reductase gene is not a major risk of coronary artery disease or myocardial infarction. 905 Dec 3

An elevated plasma homocysteine level may result from various environmental and genetic factors. Herediatary causes of severe hyperhomo-cysteinaemia are very rare and usually lead to disease in childhood or adolescence. Common pathology consists of early atherosclerotic vascular changes, arterioocclusive complications and venous thrombosis. Mildly elevated genetically determined plasma homocysteine levels are observed in 5% of the general population. In the last two decades research has shown mild hyperhomocysteinaemia to be linked to an increased risk of premature atherosclerosis, pregnancies complicated by neural tube defects and early pregnancy loss, and venous thrombosis. Homozygosity for thermolabile MTHFR deficiency has been identified as one important genetic factor, which expression is modified by dietary folate intake. Although mild hyperhomocysteinaemia can easily be treated by vitamin supplementation the beneficial effects of such treatment remains to be shown.
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PMID:Hyperhomocysteinaemia and associated disease. 925 28

Homozygotes (TT genotype) for the C677T mutation in the gene of methylenetetrahydrofolate reductase (C677T/MTHFR mutation) constitute about 12% of the Caucasian population. They have mild hyperhomocysteinemia which is an established risk factor for cardiovascular disease. If the mutation is associated with premature death its prevalence is expected to be lower in the elderly than in the young. To test this we determined the C677T/MTHFR genotypes in 220 newborn and 222 elderly 80-108-year-old Swedes. In the newborn and elderly, the allele frequency, of the C677T/MTHFR mutation was 29.1 and 27.0% and the mutant homozygote frequency was 10.0 and 9.5%, respectively. In a meta analysis of the present and three previous studies including a total of 1388 elderly and 1415 younger subjects, the odds ratio (OR) representing the likelihood of the TT genotype to attain old age relative to the CC genotype was 0.87 (95% confidence interval (CI), 0.69-1.11) and relative to both the CC and CT genotypes was 0.83 (95% CI, 0.66-1.04). This finding does not suggest that the C677T/MTHFR mutation is a strong risk factor for diseases frequently leading to premature death.
Atherosclerosis 1998 Dec
PMID:A common methylenetetrahydrofolate reductase gene mutation and longevity. 1053 96

Homocysteine is associated with atherosclerosis and enhanced cardiovascular risk. In previous studies, treatment with folic acid up to 15 mg/d failed to correct hyperhomocysteinemia in the majority of end-stage renal disease patients. A dose of 30 or 60 mg of folic acid per day was compared with 15 mg/d in an attempt to normalize hyperhomocysteinemia in 150 hemodialysis patients. In a randomized, double-blind, multicenter study, 144 patients completed the 4-wk treatment period and 121 patients completed the 6-mo follow-up. Total homocysteine plasma levels were reduced by 32.1% (15 mg/d), 29. 9% (30 mg/d), or 37.8% (60 mg/d) with no significant differences found between the three treatment groups. Baseline total homocysteine plasma concentration was an independent predictor of the response to folic acid therapy (P = 0.0001), whereas the 5, 10-methylenetetrahydrofolate reductase polymorphisms (MTHFR 677C --> T and 1298A --> C) had no influence. Nevertheless, patients with the MTHFR 677TT genotype more frequently attained normal total homocysteine plasma levels than patients with the CC or CT genotype (P = 0.025). In response to 60 mg of folic acid per day, TT genotype patients had lower folate plasma levels compared to CC or CT genotype patients (P = 0.016). After completion of the 4-wk treatment period with 30 or 60 mg of folic acid per day, there was a marked rebound of total homocysteine plasma levels at the end of the follow-up in patients with the MTHFR 677TT genotype, which even exceeded baseline values in several patients (P = 0.0001). This study clearly demonstrates that doses of 30 or 60 mg of folic acid per day are not more effective than 15 mg/d in reducing hyperhomocysteinemia in regular hemodialysis patients. Patients with the MTHFR 677TT genotype are more likely to realize normal total homocysteine plasma levels. Folic acid at 30 or 60 mg/d but not 15 mg/d results in a rebound of total homocysteine plasma concentrations when treatment is stopped.
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PMID:Effect of high dose folic acid therapy on hyperhomocysteinemia in hemodialysis patients: results of the Vienna multicenter study. 1082 Jan 75

Although three common MTHFR polymorphisms (C677T, A1298C, T1317C) have been reported, only polymorphism C677T has been investigated intensively as a risk factor for coronary artery disease (CAD). We investigated polymorphism frequencies, allelic associations and the effect of the resulting MTHFR genotypes on total plasma homocysteine (tHcy) levels and on coronary risk in a case-control study with 1000 angiographically confirmed Middle-European CAD patients and 1000 matched controls. Three out of four theoretically possible MTHFR haplotypes were detected: *1 (677C, 1298A), *2 (677T, 1298A), and *3 (677C, 1298C). The frequencies were *1: 36.4 and 34.4%; *2: 30.8 and 32.3%; and *3: 32.8 and 33.3%, in cases and controls, respectively. Only one patient was heterozygous for 1317C. None of the six resulting genotypes showed significant influence on tHcy levels. Moreover, there was no significant association with CAD risk or with disease severity or early disease manifestation. In the subgroup presenting with acute coronary syndromes, MTHFR genotypes *2/*3 and *3/*3 were surprisingly underrepresented (relative risk of *3/*3, 0.40; 95% confidence interval 0.20-0.79, P=0.009). We conclude from our genotype-based analysis that, in this well-fed Middle-European population, the observed common allelic variants of the MTHFR gene have no significant influence on tHcy levels or on the chronic process of CAD development.
Atherosclerosis 2001 Feb 15
PMID:Identification of six methylenetetrahydrofolate reductase (MTHFR) genotypes resulting from common polymorphisms: impact on plasma homocysteine levels and development of coronary artery disease. 1125 66

In this investigation associations of gene complexes consisting of seven candidate for coronary atherosclerosis (ACE, AGT, NOS3, APOA1, MTHFR, PLAT, F13) with risk factors for CAD (lipid levels, blood pressure, body mass index (BMI)) were studied in Russian population. 94 male patients with CAD proven by angiography and 131 healthy individuals were involved in the case-control study. We observed a significant contribution of gene combinations ("ensembles"). ACE-MTHFR, ACE-F13, ACE-AGT-MTHFR in the variability of the total cholesterol and LDL-cholesterol levels. The "Ensembles" ACE-AGT-MTHFR were associated with variability of three atherogenic risk factors (LDL, BMI, cholesterol total). Two-locus gametic disequilibrium was analysed between gene polymorphisms. NOS3 and ACE, NOS3 and APOA1 were in gametic disequilibrium in the control group. Polymorphic markers of ACE and F13, NOS3 and F13, ACE and PLAT loci were in gametic disequilibrium in the patients. Both approaches (association analysis and gametic disequilibrium) revealed the same gene combinations contributing to the CAD risk factors. NOS3 and APOA1 markers were in gametic disequilibrium in the patients and both of them were associated with LDL. F13 and AGT were associated with systolic and diastolic blood pressure and two-locus gametic disequilibrium between F13 and AGT polymorphisms observed in the patients.
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PMID:The estimation of gametic disequilibrium between DNA markers in candidate genes for coronary artery disease (CAD) and the associations of gene complexes with risk factors for CAD. 1150 73

The following seven polymorphic marker loci of genes responsible for predisposition to coronary atherosclerosis (CAS) were studied: the ACE locus responsible for angiotensin-converting enzyme insertion/deletion polymorphism for the presence or absence of the Alu insertion in the gene; the F13, PLAT, and APOA1 loci, controlling the clotting factor 13, plasminogen-activating tissue factor, and apolipoprotein A, respectively; the MTHFR and AGT polymorphic loci responsible for point mutations in methylenetetrahydrofolate reductase and those in angiotensinogen, respectively, and the NOS3 locus controlling the number of tandem repeats in the nitric oxide synthase gene. These loci are located on different chromosomes and encode products involved into various metabolic pathways leading to CAS. In the populations studied, significant differences between healthy subjects and patients predisposed to cardiovascular diseases were revealed with regard to the above seven markers. The 174M allele (T174M polymorphism in the ACE gene) was significantly associated with coronary atherosclerosis. It was found that specific gene combinations are involved in the CAS development and determine variation in the pathogenetically important quantitative traits.
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PMID:[Analysis of gene complexes predisposing to coronary atherosclerosis]. 1196 67

Hyperhomocysteinemia is an accepted risk factor for coronary artery disease, but the determining factors are not fully understood. We investigated hyperhomocysteinemia and vitamin deficiency in Syrian coronary patients and apparently healthy Syrian and German controls. We enrolled 273 Syrian patients with angiographically confirmed stenosis, along with 159 Syrian and 75 German controls. Plasma total homocysteine (HCY), cystathionine, methylmalonic acid (MMA), vitamin B-6, B-12, folate, lipids, apolipoproteins and methylenetetrahydrofolate reductase (C677T-MTHFR) mutation were analysed. There was a very high prevalence of hyperhomocysteinemia (>12 micromol/l) in Syrians (patients 61%, controls 44%, Germans 16%) together with functional vitamin B-12 deficiency diagnosed by elevated MMA (patients 49%, controls 47%, Germans 3%), which was in contrast to the low frequency of decreased serum vitamin B-12 (12% in patients, 7% in Syrian controls). The HCY concentration in German controls was lower than in Syrians, median 8.8 vs. 11.3 micromol/l. The vitamin B-12 deficiency induces folate trapping; higher levels of folate are needed to prevent hyperhomocysteinemia. Germans achieved the HCY level of < or =12 micromol/l at significantly lower folate concentrations > or =4.4 ng/ml, than Syrians with normal MMA (> or =16.7 nmol/l folate) or Syrians with high MMA (> or =23.3 nmol/l folate). Smoking and homozygous state for C677T-MTHFR mutation contributed to hyperhomocysteinemia. We could confirm that the reasons for hyperhomocysteinemia in Syrians were in fact mostly related to a relative folate deficiency, which is due to a vitamin B-12 shortage. Vitamin B-12 deficiency induces folate trapping. Besides lifestyle, other presently unknown factors may contribute to hyperhomocysteinemia and vitamin B-12 deficiency in Syrians.
Atherosclerosis 2003 Jan
PMID:Hyperhomocysteinemia and vitamin B-12 deficiency are more striking in Syrians than in Germans--causes and implications. 1248 61

Atherosclerosis is an important medical problem of the 21st century, but traditional risk factors could only account for 50% of the problem. Hyperhomocysteinemia is emerging as an independent atherosclerosis risk factor, associated with folate deficiency, renal failure, and relative deficiency of MTHFR (C677T polymorphism) or other enzymes depending on gender, age, and smoking status. Hyperhomocysteinemia has been reported to occur in 11-22% of western people, in 3-5% of normal asymptomatic Chinese subjects aged 18-70 years in Hong Kong, Macau, Sydney, and San Francisco, 23-36% of Chinese in Hong Kong with premature coronary artery disease, and 29% of a nonselective series of coronary subjects in Hong Kong. Evidence is accumulating that documents its associations with atherosclerosis disease in both case-control observations and prospective cohort studies, in vitro experiments, and in vivo experimental models in both animals and human subjects, as well as the successful improvement by homocysteine-lowering of endothelial function as surrogate atherosclerosis endpoints in asymptomatic human and coronary patients (secondary prevention). A number of large scale homocysteine-lowering trials are currently underway for stroke and heart attacks prevention. Collectively these trials will include more than 65,000 patients at high-risk for cardiovascular and stroke events, and should provide a reliable evidence-base for prevention.
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PMID:Homocysteine, endothelial dysfunction, and coronary artery disease: emerging strategy for secondary prevention. 1263 May 44

Hyperhomocysteinemia is considered one of the emerging risk factors for the development of coronary artery disease (CAD). In order to know the prevalence of this metabolic disorder in a Mexican population with early CAD (< 50 years), we studied a group of these patients and compared the levels of homocysteine with a group of patients, paired by age and gender, without angiographic evidence of coronary atherosclerosis. Preliminary results show that the population with early CAD has more traditional risk factors, specially diabetes mellitus, and higher levels of homocysteine in plasma. Moreover there is a genetic factor with higher incidence of a TT homozygotic mutation of the MTHFR that increases homocysteine because of an altered folate metabolism.
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PMID:[Hyperhomocysteinemia as risk factor in a Mexican population]. 1296 56


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